1. Field of the Invention
The present invention relates to king pin locks, and more particularly pertains to a new and improved king pin lock to prevent unauthorized movement of a trailer when detached from a tractor. Conventional tractor-trailer trucking rigs utilize a cylindrical king pin having an exterior circumferential groove which extends downwardly from a bottom surface at the front edge of the trailer. The trailer king pin is received in a central aperture in the fifth wheel portion of the towing tractor vehicle. The trailers are frequently left unattended in large numbers in both loaded and unloaded conditions. Previously, the theft of such unattended trailers has been a large problem, because it is a simple matter to attach a tractor and merely drive away. In order to overcome this problem, the present invention provides a locking device which attaches to the king pin of a trailer to prevent engagement in the fifth wheel of a towing tractor.
2. Description of the Prior Art
Various types of king pin locks are known in the prior art. A typical example of such a king pin lock is to be found in U.S. Pat. No. 4,141,233, which issued to E. Reyes on Feb. 27, 1979. This patent discloses a king pin lock which includes locking collar halves each having a semi-annular body portion adapted for engagement with the circumferential exterior groove of a trailer king pin. One of the body portions is provided with an S-shaped flange having a hook end engagable in a slot on a flange on the other collar half. A padlock hasp is utilized to secure the two halves together. U.S. Pat. No. 4,553,415, which issued to C. Maffey on Nov. 19, 1985, discloses a king pin lock having a cylindrical body member provided with a central bore dimensioned to receive a king pin. A locking bar is inserted within a transverse aperture which communicates with the central bore and has an inner end adapted to be engaged within the king pin circumferential groove. The locking bar is secured in place by a key actuated locking cylinder. U.S. Pat. No. 4,620,718, which issued to T. Mickelson on Nov. 4, 1986, discloses a king pin lock which includes a body member provided with a longitudinal bore dimensioned to receive a cylindrical king pin of a trailer. A locking bar having an arcuate end portion adapted for engagement in the circumferential groove of the king pin is received in a transverse slot communicating with the central bore. A padlock is utilized to secure the locking bar in place. U.S. Pat. No. 4,697,444, which issued to C. Maffey on Oct. 6, 1987, discloses a king pin lock which includes a body member provided with a longitudinal bore and an intersecting transverse bore which receives a key actuated locking cylinder having an inner end dimensioned for engagement with the circumferential groove of a king pin. U.S. Pat. No. 4,704,883, which issued to J. Dikeys on Nov. 10, 1987, discloses a king pin lock which includes a cylindrical body member having a longitudinal bore dimensioned to receive a cylindrical trailer king pin. A transverse intersecting bore receives a key actuating locking cylinder having an inner end dimensioned for engagement in the circumferential groove of the king pin.
While the above mentioned devices are addressed to the solution of the same problem as the present invention, none of these devices provide a locking mechanism which engages a major circumferential portion within the circumferential groove of the king pin. Additionally, many of the above described devices feature exposed locking mechanisms which may be easily removed utilizing bolt cutters, hack saws or cutting torches. The present invention overcomes these disadvantages by providing a completely enclosed locking mechanism which is well protected from damage by theft attempts. Further, the present invention utilizes arcuate locking arms, actuated by a cam mechanism, which engage a major circumferential portion in the circumferential groove of a king pin, and provide an enhanced securement of the lock to the king pin. Inasmuch as the art is relatively crowded with respect to these various types of king pin locks, it can be appreciated that there is a continuing need for and interest in improvements to such king pin locks, and in this respect, the present invention addresses this need and interest.